Process of refining hydrocarbon oils



Patented Oct. 31, 1939 UNITED STATES PROCESS OF REFINING HYDROCARBON OILS Ernst Terres, Berlin, Germany, and Josef Moos, New York, and Erich Saegebarth, Jackson Heights, N. Y., assignors, by mesne assignments, to Edeleanu Gesellschaft, m. b. H., Berlira, Germany, a corporation of Germany No Drawing. Qriginal application March 22,

1935, Serial No. 12,526. Divided and this application Cctober 25,

1937, Serial No. 170,968.

In France March 21, 1936 7 Claims.

This invention relates to the refining of hydrocarbon oils, such as mineral oils, and oils made from coal tar and bituminous coal tar, and is a division of our application Ser. No. 12,526, filed March 22, 1935, now U. S. Patent No. 2,145,185, dated Jan. 24, 1939.

In particular this invention relates to refining hydrocarbon oils by means of selective solvents. Selective solvents have been used heretofore for this purpose and their action consists in dissolving the undesirable fractions which contain mainly aromatic, hydro-aromatic and unsaturated hydrocarbons, so that the remaining non-dissolved fraction or rafinate shows greatly improved specifications.

We have found that acetanilide (methyl formanilide) is very suitable for refining hydrocarbon oils, such as mineral oils, coal tar or bituminous coal tar oils or fractions thereof.

In carrying out our invention we may employ either a countercurrent tower mixer or an equipment consisting of mixing and settling stages, in order to contact the hydrocarbon oils to be extracted with the solvent and thoroughly commingle them. The hydrocarbon oils and the desired quantity of our solvent are introduced into the treating system in such a way that the well known countercurrent washing efiect is obtained.

As an illustration of the effect of our solvent we mention the following examples. It is to be understood that these examples serve as an indication only and do not cover the entire scope of our invention.

Example 1 A dewaxed California lubricating oil with specifications as shown below was extracted at 120 C. in the normal manner with 150+3 50 volume-per cent acetanilide (methylformanilide) having a melting point of 113.6 C. and a boiling point of 303.8 C. After separating the phases and removing the solvent therefrom a refined oil was obtained as shown in the table below under (a).

Example 2 A sample of the same California lubricating oil was extracted with 150+3 50 volume-per cent acetanilide at 150 C. Specifications of the raffinate after removal of the solvent are listed in the table below under (12).

Example 3 A sample of the same California lubricating oil as used above was extracted with 200+3 100 volume-per cent acetanilide at 120 C. For tests of the refined oil refer to column in the fol- I lowing table:

On account of its high boiling point acetanilide cannot conveniently be removed from raffinate and extract solutions by distillation. A very convenient means of solvent recovery is to wash the raffinate and extract-solutions repeatedly, or in countercurrent manner, with hot water in which 5.6% acetanilide, based on the amount of water, is soluble. In cold water acetanilide is practically insoluble (0.56%). In the continuous process the ramnate and extract solutions are washed with hot water in separate washing towers of conventional design, the hot-water-acetanilide solution is cooled to room temperature whereupon the acetanilide crystallizes out. The solid acetanilide is filtered from the solution by conventionally used filter apparatus, preferably rotating filters, melted and heated to the temperature at which the extraction is carried out. The water is likewise heated close to its boiling point and re-used in the washing step.

For removing acetanilide from the extract solution preferably mixtures of methanol and water are used, containing for example 50 volume-per cent methanol and 50 volume-per cent water. These methanol-water blends have a greater solubility for acetanilide than water alone, without dissolving appreciable amounts of the lubricating oil extract, This is advantageous, especially in working-up extract solutions which contain large quantities of solvent, because thereby the amount of necessary washing liquor is greatly reduced. The removal of acetanilide from raifinate and extract solutions by means of washing same with water or mixtures of water and an alcohol, may also be effected at super-atmospheric pressures and at temperatures above 212 F.

In some cases we prefer to employ acetanilide in the presence of auxiliary solvents. The auxiliary solvents we divide into two classes.

Class 1 of the auxiliary solvents is characterized by being entirely miscible in any proportion with our selective solvent and also with the hydrocarbon oils to be treated. Representatives tit) of this class are the aromatics, hydroaromatics, the non-selective aliphatic and aromatic halogen derivatives, the non-selective ketones, ethers, and others. On account of the miscibility in our selective solvent and in the hydrocarbon oils, this class of auxiliary solvents serves to increase the solvent power of our selective solvent.

In other cases we prefer to decrease the solvent power of our selective solvent. This is, for example, feasible in treating naphthene base oils which contain a large percentage of the undesirable fraction or extract. For this purpose we employ class 2 of auxiliary solvents which are identified by being entirely miscible with our selective solvent but not or only a little miscible with the hydrocarbon oils to be extracted. Representatives of this class are, for example, alcohols and water.

The solvents may be recovered from the railinate and extract layer by washing with hot water or, instead, we may also employ one or more other solvents which dissolve out selective and auxiliary solvents but which do not dissolve the hydrocarbon oils.

Having thus described our invention, what we claim is:

1. A process for refining hydrocarbon oils to increase the viscosity index thereof by extracting the latter with a mixture containing acetanilide in preponderant amount at suitable temperatures to produce a separation into two layers containing respectively parafiinic and nonparafiinic constituents, separating the layers from each other and recovering the solvent from the layers.

2. A process for refining hydrocarbon oils to increase the viscosity index thereof by solvent extraction in which acetanilide is used in preponderant amount in presence of an added auxiliary solvent which is miscible in any proportion with the acetanilide and with the hydrocarbon oils, the addition of said auxiliary solvent resulting in an increased solvent power of the solvent blend, to produce a separation into two layers containing respectively paraifinic and non-paraifinic constituents, and separating the layers from. each other.

3. A process according to claim 2 in which the auxiliary solvent or solvents are representatives of the class of aromatics, hydroaromatics, and the non-selective aromatic halogen derivatives.

4. A process for refining hydrocarbon oils by solvent extraction in which acetanilide is used in presence of an auxiliary solvent which is miscible with the acetanilide but which is not miscible beyond a small degree, with the hydrocarbon oils to be extracted, the addition of said auxiliary solvent decreasing the solvent power of the solvent blend.

5. A process, according to claim 4, in which the auxiliary solvent comprises alcohol.

V 6. A process, according to claim 4, in which the auxiliary solvent comprises water.

7. A process for refining lubricating oil containing paraflinic and non-parafiinic constituents to increase the viscosity index thereof, comprising extracting said lubricating oil with a mixture containing acetanilide in preponderant amount as a selective solvent at a temperature of above 114 degrees centigrade to produce a dissolved layer consisting of the non-paraffinic oil constituents dissolved in the bulk of the selective solvent, and an undissolved layer consisting of the paraflinic oil constituents saturated with the selective solvent, separating the dissolved layer from the undissolved layer and removing the solvent from both layers.

ERNST TERRES. JOSEF MOOS. ERICH SAEGEBARTl-I. 

